In the production of injection-molded synthetic-resin articles of reactive components it is necessary to mix together the two components immediately before or as they are introduced into the cavity of the mold. The reaction is frequently relatively violent and involves the generation of gases which can cause the mixture to bubble considerably. As a rule the two components mix together in a mixing chamber and are then fed via a quieting chamber to the mold cavity.
In one known arrangement the quieting chamber has two lobes acting as diffusers. This quieting chamber must further be formed with a relatively narrow mouth opening into the mold so that the sprue formed thereby on the molded body will be readily removable.
The principal difficulty with this system is that the material hardens within the quieting chamber each time the apparatus is cycled so that additional mechanism must be provided to flush and/or punch out the hardened material. Such mechanism considerably increases the cost of the apparatus.
Another disadvantage of such a system is that the molding material is fed into the mold cavity while still reacting so that this material frequently bubbles up in the mold cavity and indeed overflows this cavity. As a matter of fact it is not uncommon in such systems to lose more than half the workpieces or to be required to cut down and machine the workpieces after molding so as to be able to use them.